15 replies to this topic

[david_vennard]

Hello it's been a long time since I've been on this!
I'll sum this up quickly,I got a rebuilt engine and gearbox from a guy "hes a mini guy, runs his own business etc" now the engine was rebuilt and put in to the car. Now this is back June/July 2012.

Its needed work from near day one. Crunching from 4th to 3rd and a leak from the crank shaft oil seal.
And I was always told just keep and eye on the oil it did about 60miles to a pint of oil on a run ....

Now to jump forward.To September 2013/2014

He had the plan that he would rebuild me another engine to use while he rebuilt the the other one and once Thats fixed swap them back.I had been told alot of times yes the engine is in the process of being rebuilt....but I've never seen or been shown it

But now I've changed from 12in to 10in wheels to he's saying that the gearbox he built up won't be right. As he built it for 12inch wheels. Now I know there is a slight difference in the ratio/and speedo. But I don't see people going to 12in to 10s and having to do anything with the box.... Guys help me out!
Cheers vinni

[Fast Ivan]

the only thing that may need changing is the speedo worm and pinion gear, what ones you will need will depend on the final drive and the size of wheels, but the cost in parts should they need changing is about £30.
if you look here http://www.guess-wor.../Tech/ratio.htm

guessworks can also supply the parts

[mr cooke]

I dont think its a problem , I went from 10's to 13's no probs other then the speedo is out

Edited by mr cooke, 26 January 2014 - 12:12 PM.

[RossKnight]

barely any difference in tyre size from 12's to 10, rolling radius won't effect it that much surely? 

[welshdan]

I changed my speedo drive gears with the engine/box insitu.

[carbon]

David - do you know what final drive ratio you have fitted in this gearbox?

 

As with above replies, a change to 10 inch wheels will make the engine spin slightly faster at a given road speed but this should not make a big difference.

 

However it sounds like the rebuilt gearbox has other issues that need sorted. Does the guy doing the work specialise in Minis?

[Cooperman]

The difference between a 165/60 x 12 tyre and a 165/70 x 10 tyre is 3.5%, with the speedo reading 3.5% higher with the 10" tyre.

So at 60 the speedo will be reading 62 mph with the 10" as opposed to the 12". Sine Mini speedos are very inaccurate you simply won't notice any difference, so don't spend money you don't need to.

 

To do the calculation yourself, the 165 refers to the width of the tyre and the 60 or 70 gives the aspect ratio. So to find the tyre sidewall nominal height, you take either 60% or 70% of the 165. Then divide that by 25.4 to get it in inches and add the radius of the wheel, 6" for a 12" wheel and 5" for a 10" wheel. That gives the rolling radius, which is what you are interested in.

 

So, a 165/70 x 10 is calculated thus:  (165 x 0.7) divided by 25.4 plus 5 = rolling radius in inches.

 

I hope this helps.

[david_vennard]

David - do you know what final drive ratio you have fitted in this gearbox?
 
As with above replies, a change to 10 inch wheels will make the engine spin slightly faster at a given road speed but this should not make a big difference.
 
However it sounds like the rebuilt gearbox has other issues that need sorted. Does the guy doing the work specialise in Minis?

Not sure what final ratio is in atm, he couldnt even tell me what cam he put in the engine other that it was a sports cam.
I've emailed him that,I know it wouldnt make a big difference if any noticeable difference that you would have to change parts in the box, I'm awaiting to hear back from him. The gearbox does need fixed think the idler gear is causing the crunch and leaking all the time from the crank shalf oil seal.And also leaking from the head gasket too
The guy doing the work has specialised in minis for 30odd years....

Edited by david_vennard, 26 January 2014 - 08:53 PM.

[david_vennard]

The difference between a 165/60 x 12 tyre and a 165/70 x 10 tyre is 3.5%, with the speedo reading 3.5% higher with the 10" tyre.
So at 60 the speedo will be reading 62 mph with the 10" as opposed to the 12". Sine Mini speedos are very inaccurate you simply won't notice any difference, so don't spend money you don't need to.
 
To do the calculation yourself, the 165 refers to the width of the tyre and the 60 or 70 gives the aspect ratio. So to find the tyre sidewall nominal height, you take either 60% or 70% of the 165. Then divide that by 25.4 to get it in inches and add the radius of the wheel, 6" for a 12" wheel and 5" for a 10" wheel. That gives the rolling radius, which is what you are interested in.
 
So, a 165/70 x 10 is calculated thus:  (165 x 0.7) divided by 25.4 plus 5 = rolling radius in inches.
 
I hope this helps.

It does help, when he did said that the one he built up was for 12in wheels and won't work with 10in I knew that wasn't right lots of people change from 10s to 13s and vise versa and I've never seen people marking it as an issue that the gearbox needs to be changed/altered . We've a 1982mini auto with 13in wheels and the only thing wrong is the speedo is out.

[Cooperman]

The most difference in speedo readings between 10", 12" and 13" wheels in no more than 3.5%. There is almost that difference between new & just-legal tyres on the same size rims anyway. In fact the 165/60 x 12 & the 175/50 x 13 give virtually identical rolling radii - do the maths yourself and the 10" will be 3.5% higher speed reading. That is assuming the same state of tyre wear.

Of course, a couple of PSI difference in tyre pressures can give a similar difference.

It really is not an issue at all.

[Fast Ivan]

I would be gathering up my stuff and walking away from this guy

[Cooperman]

It does seem as though the 'mini guy' mentioned by the OP doesn't know his ass from his elbow. Clearly he didn't build it properly in the first place, didn't immediately correct his poor workmanship, doesn't understand the way to calculate tyre rolling radii and their effect on overall gearing, doesn't know what cam he fitted and didn't check the FDR before building (or maybe not building) the gearbox.

Personally I wouldn't let him within 100 yards of my Minis!

[KernowCooper]

100yds Pete, you'd wouldn't let him in the same town. Specialised in Minis for 30+ years and you got all those issues ? I'd certainly not be letting him build another. I know a specialist round here who tests batteries by how much spark there is between the positive and negative.

 

When I did my apprenticeship my Father said pay attention to the work they do and not what they say they do, always worked for me,

[david_vennard]

i would to be honest do the work myself and my mini club, but he has made it clear "do not touch that engine" "warrenty" and the only reason i havent just walked away is as the engine + fitting wasnt cheap.

 

im just going to have to wait until he gets back to me and see what sort of story he comes up with. just the whole rigmaroll of it from the engine being being rebuilt and needed fixed from then in 2012, and we where suppost to get the engine sorted last year after the show season " september time, that never came, never had space, always busy,  he'll contact me and so on, just got keep an eye on the levels.

 

this isnt anyway to run a business, im sure if i was a customer wanting an engine rebuild and had 600 quid he'd get me in with in a week or two. but as its underwarrenty hes being awkward about the whole thing.

[Cooperman]

David,

 

You could and probably should give him a specific and reasonable time scale for carrying out the rectification work due to you under his warranty. Reasonable could be delivered back to you within, say, 6 weeks. He should be told that failure to do so will result in your getting the work done elsewhere and then you sending the bill to him.

If he then fails to do the work you will win in court, if it go that far.

Personally I find 'shysters' like this unacceptable in our World of Minis and the sooner he realises that he obviously knows less than is required in repairing & restoring these increasingly valuable classic cars the better.

 

God luck with this.